Optical systems have many applications, including communication and materials processing. Such optical systems often employ lasers, for example, fiber lasers, disk lasers, diode lasers, diode-pumped solid state lasers, and lamp-pumped solid state lasers. In these systems, optical power is often delivered by an optical fiber.
An optical modulator is a device often included in an optical system where a parameter or characteristic of the light is to be varied over time. Some modulators are useful for varying an intensity (amplitude) of a light beam exiting the optical modulator. Some such modulators are absorptive modulators and refractive modulators. Some absorptive modulators include a material that has an absorption coefficient which can be manipulated, for example through Franz-Keldysh effect, or the Quantum-confined Stark effect (QCSE). Some refractive modulators include a material that displays an acousto-optic effect where an index of refraction is modulated via an acoustic wave, or a magneto-optic effect where polarization of a material is modulated via a quasistatic magnetic field. Such phase modulation can then be converted into an intensity modulation.
Conventional optical modulators exemplified above typically employ free-space or bulk optical components, which come with an associated cost, increase in optical system complexity, inherent optical losses, and/or reliability constraints. A fiber-based, or “all-fiber,” optical modulator is advantageous as eliminating one or more of the constraints associated with free-space optical modulators.